Effect of Deposition Temperature on the Electrochromic Properties of Electron Beam-Evaporated WO3 Thin Films

Abstract

Tungsten oxide (WO3) thin films were deposited on ITO/glass substrates using the electron beam evaporation technique. The WO3 films were grown on substrates at temperatures varying from room temperature (RT) to 240 °C. The structural characterization and surface morphology were examined using X-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The electrochromic properties of WO3 thin films were investigated using cyclic voltammograms (CVs) and in situ transmittance measurements, which were performed on WO3 thin films immersed in an electrolyte of 1 M LiClO4 in propylene carbonate (PC). An amorphous 510-nm-thick WO3 film heated at RT exhibits the maximum transmittance variation (ΔT%) of 61.8% between the bleached state and the colored state, with a ΔOD of 0.739, Q of 17.31 mC/cm2 and η of 42.69 cm2/C at a wavelength (λ) of 550 nm.